Albert Barnes Commentary Jeremiah 51:7

"Babylon hath been a golden cup in Jehovah`s hand, that made all the earth drunken: the nations have drunk of her wine; therefore the nations are mad." — Jeremiah 51:7 (ASV)

Literally, “A golden cup is Babel in the hand of Yahweh, intoxicating the whole earth.” Jeremiah beholds her in her splendor, but the wine with which she makes the nations drink is the wrath of God. As God’s hammer (Jeremiah 50:23), Babylon was strong: as His cup of gold, she was rich and beautiful, but neither saves her from ruin.